A251204 Number of (n+1) X (2+1) 0..2 arrays with every 2 X 2 subblock summing to a nonzero multiple of 2.

180, 1246, 8870, 65040, 489772, 3775022, 29664576, 236740252, 1912108322, 15584536740, 127880485540, 1054537633526, 8727275684760, 72413361371620, 601955189383922, 5010545177519292, 41746084890460636, 348047155647060662

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 18*a(n-1) - 90*a(n-2) + 7*a(n-3) + 576*a(n-4) + 210*a(n-5) - 180*a(n-6).

Empirical g.f.: 2*x*(90 - 997*x + 1321*x^2 + 8130*x^3 + 2475*x^4 - 2430*x^5) / ((1 - 6*x)*(1 - 5*x - 5*x^2)*(1 - 7*x - 12*x^2 + 6*x^3)). - Colin Barker, Nov 27 2018

Example

Some solutions for n=4:
..2..2..0....0..2..2....2..2..0....1..1..1....1..0..2....0..2..2....2..0..2
..0..0..0....2..0..2....2..2..0....0..2..2....1..0..2....0..2..2....2..2..0
..0..2..0....1..1..1....2..0..0....2..2..0....1..2..0....2..0..2....0..2..0
..0..2..2....2..2..2....0..2..0....2..2..2....1..2..0....0..2..0....2..0..0
..2..2..0....2..0..2....0..0..0....2..0..2....1..0..2....1..1..1....1..1..1

Crossrefs

Column 2 of A251210.

Sequence in context: A032774 A032776 A251255 * A225933 A225932 A081380

Adjacent sequences: A251201 A251202 A251203 * A251205 A251206 A251207

Keyword

nonn

Author

R. H. Hardin, Nov 30 2014

Status

approved